diff --git a/tests/suites/test_suite_ctr_drbg.function b/tests/suites/test_suite_ctr_drbg.function
index 7f7d4950de..714af5598b 100644
--- a/tests/suites/test_suite_ctr_drbg.function
+++ b/tests/suites/test_suite_ctr_drbg.function
@@ -3,6 +3,15 @@
 #include "mbedtls/ctr_drbg.h"
 #include "string.h"
 
+/* Modes for ctr_drbg_validate */
+enum reseed_mode
+{
+    RESEED_NEVER, /* never reseed */
+    RESEED_FIRST, /* instantiate, reseed, generate, generate */
+    RESEED_SECOND, /* instantiate, generate, reseed, generate */
+    RESEED_ALWAYS /* prediction resistance, no explicit reseed */
+};
+
 static size_t test_offset_idx;
 static size_t test_max_idx;
 static int mbedtls_test_entropy_func( void *data, unsigned char *buf, size_t len )
@@ -55,74 +64,107 @@ exit:
 /* END_CASE */
 
 /* BEGIN_CASE */
-
-/* BEGIN_CASE */
-void ctr_drbg_validate_no_reseed( char *add_init_string, char *entropy_string,
-                                  char *add1_string, char *add2_string,
-                                  char *result_string )
+void ctr_drbg_validate( int reseed_mode, char *nonce_string,
+                        int entropy_len_arg, char *entropy_string,
+                        char *reseed_string,
+                        char *add1_string, char *add2_string,
+                        char *result_string )
 {
-    unsigned char entropy[512];
-    unsigned char add_init[512];
-    unsigned char add1[512];
-    unsigned char add2[512];
+    unsigned char entropy[144];
+    unsigned char nonce[64];
+    unsigned char reseed[32];
+    unsigned char add1[48];
+    unsigned char add2[48];
     mbedtls_ctr_drbg_context ctx;
-    unsigned char buf[512];
-    unsigned char result[512];
-    size_t entropy_len, add_init_len, add1_len, add2_len, result_len;
+    unsigned char buf[64];
+    unsigned char result[64];
+    size_t entropy_chunk_len = (size_t) entropy_len_arg;
+    size_t nonce_len, reseed_len, add1_len, add2_len, result_len;
 
+    test_offset_idx = 0;
     mbedtls_ctr_drbg_init( &ctx );
 
-    entropy_len = unhexify( entropy, entropy_string );
-    add_init_len = unhexify( add_init, add_init_string );
+    test_max_idx = unhexify( entropy, entropy_string );
+    nonce_len = unhexify( nonce, nonce_string );
+    reseed_len = unhexify( reseed, reseed_string );
     add1_len = unhexify( add1, add1_string );
     add2_len = unhexify( add2, add2_string );
     result_len = unhexify( result, result_string );
 
-    test_offset_idx = 0;
-    test_max_idx = entropy_len;
     /* CTR_DRBG_Instantiate(entropy[:entropy_len], nonce, perso, <ignored>)
-     * where nonce||perso = add_init[add_init_len] */
-    TEST_ASSERT( mbedtls_ctr_drbg_seed_entropy_len( &ctx, mbedtls_test_entropy_func, entropy, add_init, add_init_len, entropy_len ) == 0 );
+     * where nonce||perso = nonce[nonce_len] */
+    TEST_ASSERT( mbedtls_ctr_drbg_seed_entropy_len(
+                     &ctx,
+                     mbedtls_test_entropy_func, entropy,
+                     nonce, nonce_len,
+                     entropy_chunk_len ) == 0 );
+    if( reseed_mode == RESEED_ALWAYS )
+        mbedtls_ctr_drbg_set_prediction_resistance(
+            &ctx,
+            MBEDTLS_CTR_DRBG_PR_ON );
+
+    if( reseed_mode == RESEED_FIRST )
+    {
+        /* CTR_DRBG_Reseed(entropy[idx:idx+entropy_len],
+         *                 reseed[:reseed_len]) */
+        TEST_ASSERT( mbedtls_ctr_drbg_reseed(
+                         &ctx,
+                         reseed, reseed_len ) == 0 );
+    }
 
     /* CTR_DRBG_Generate(result_len * 8 bits, add1[:add1_len]) -> buf */
-    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, buf, result_len, add1, add1_len ) == 0 );
+    /* Then reseed if prediction resistance is enabled. */
+    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add(
+                     &ctx,
+                     buf, result_len,
+                     add1, add1_len ) == 0 );
+
+
+    if( reseed_mode == RESEED_SECOND )
+    {
+        /* CTR_DRBG_Reseed(entropy[idx:idx+entropy_len],
+         *                 reseed[:reseed_len]) */
+        TEST_ASSERT( mbedtls_ctr_drbg_reseed(
+                         &ctx,
+                         reseed, reseed_len ) == 0 );
+    }
+
     /* CTR_DRBG_Generate(result_len * 8 bits, add2[:add2_len]) -> buf */
-    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, buf, result_len, add2, add2_len ) == 0 );
+    /* Then reseed if prediction resistance is enabled. */
+    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add(
+                     &ctx,
+                     buf, result_len,
+                     add2, add2_len ) == 0 );
     TEST_ASSERT( memcmp( buf, result, result_len ) == 0 );
 
 exit:
     mbedtls_ctr_drbg_free( &ctx );
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void ctr_drbg_validate_no_reseed( char *add_init_string, char *entropy_string,
+                                  char *add1_string, char *add2_string,
+                                  char *result_string )
+{
+    test_suite_ctr_drbg_validate( RESEED_NEVER, add_init_string,
+                                  strlen( entropy_string ) / 2, entropy_string,
+                                  "", add1_string, add2_string,
+                                  result_string );
+    goto exit;
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ctr_drbg_validate_pr( char *add_init_string, char *entropy_string,
+                           char *add1_string, char *add2_string,
                            char *result_string )
 {
-    mbedtls_ctr_drbg_context ctx;
-    unsigned char buf[512];
-    unsigned char result[512];
-    size_t entropy_len, add_init_len, add1_len, add2_len, result_len;
-
-    mbedtls_ctr_drbg_init( &ctx );
-
-    entropy_len = unhexify( entropy, entropy_string );
-    result_len = unhexify( result, result_string );
-
-    test_offset_idx = 0;
-    test_max_idx = entropy_len;
-    /* CTR_DRBG_Instantiate(entropy[:entropy_len/3], nonce, perso, <ignored>)
-     * where nonce||perso = add_init[add_init_len] */
-    TEST_ASSERT( mbedtls_ctr_drbg_seed_entropy_len( &ctx, mbedtls_test_entropy_func, entropy, add_init, add_init_len, entropy_len / 3 ) == 0 );
-    mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );
-
-    /* CTR_DRBG_Generate(result_len * 8 bits, add1[:add1_len]) -> buf */
-    /* Then reseed because of prediction resistance. */
-    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, buf, result_len, add1, add1_len ) == 0 );
-    /* CTR_DRBG_Generate(result_len * 8 bits, add2[:add2_len]) -> buf */
-    /* Then reseed because of prediction resistance. */
-    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, buf, result_len, add2, add2_len ) == 0 );
-    TEST_ASSERT( memcmp( buf, result, result_len ) == 0 );
-
-exit:
-    mbedtls_ctr_drbg_free( &ctx );
+    test_suite_ctr_drbg_validate( RESEED_ALWAYS, add_init_string,
+                                  strlen( entropy_string ) / 6, entropy_string,
+                                  "", add1_string, add2_string,
+                                  result_string );
+    goto exit;
 }
 /* END_CASE */
 
@@ -131,32 +173,11 @@ void ctr_drbg_validate_nopr( data_t * add_init, data_t * entropy,
                              data_t * add1, data_t * add_reseed,
                              char *add2_string, char *result_string )
 {
-    mbedtls_ctr_drbg_context ctx;
-    unsigned char buf[512];
-    unsigned char result[512];
-    size_t entropy_len, add_init_len, add1_len, add_reseed_len, add2_len, result_len;
-
-    mbedtls_ctr_drbg_init( &ctx );
-
-    entropy_len = unhexify( entropy, entropy_string );
-    result_len = unhexify( result, result_string );
-
-    test_offset_idx = 0;
-    test_max_idx = entropy_len;
-    /* CTR_DRBG_Instantiate(entropy[:entropy_len/2], nonce, perso, <ignored>)
-     * where nonce||perso = add_init[add_init_len] */
-    TEST_ASSERT( mbedtls_ctr_drbg_seed_entropy_len( &ctx, mbedtls_test_entropy_func, entropy, add_init, add_init_len, entropy_len / 2 ) == 0 );
-
-    /* CTR_DRBG_Generate(16 * 8 bits, add1[:add1_len]) -> buf */
-    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, buf, result_len, add1, add1_len ) == 0 );
-    /* CTR_DRBG_Reseed(entropy[entropy_len/2:entropy_len], add_reseed[:add_reseed_len]) */
-    TEST_ASSERT( hexcmp( buf, result_str->x, 16, result_str->len ) == 0 );
-    /* CTR_DRBG_Generate(16 * 8 bits, add2[:add2_len]) -> buf */
-    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, buf, result_len, add2, add2_len ) == 0 );
-    TEST_ASSERT( memcmp( buf, result, result_len ) == 0 );
-
-exit:
-    mbedtls_ctr_drbg_free( &ctx );
+    test_suite_ctr_drbg_validate( RESEED_SECOND, add_init_string,
+                                  strlen( entropy_string ) / 4, entropy_string,
+                                  add_reseed_string, add1_string, add2_string,
+                                  result_string );
+    goto exit;
 }
 /* END_CASE */